For formulating feeds for experimental purposes, it is necessary that all ingredients are controlledfor all essential nutrients. But, under practical conditions, such a control is difficult to set forth and mostly restricted to rapid proximate composition analyses. Specific attention should however be given to obtain guarantees for absence of anti-nutritional factors, to avoid adulteration of products and for homogeneity between batches. Besides such quality control of incoming ingredients, a strict control of material flow within the factory is of utmost importance to avoid deterioration of the nutritional value (oxidation, potency of vitamins) of ingredients and premixes.
To make the 27 percent crude protein carp feed, we must mix 17/35.8 of rice bran with 18.8/35.8 soybean meal.
Rice Bran 17/35.8 = 47.5%
Soybean meal 18.8/35.8 = 52.5%
So to make 100 kg of this feed we must mix 47.5 kg of rich bran with 52.5 kg of soybean meal.
If more than two feedstuffs are used in a feed, they may be grouped into basal feeds (CP < 20 percent) and protein supplements (CP > 20 percent), averaged within each group, and
into the square method. For example, suppose shrimp meal and corn were also available for the carp feed mentioned above. The crude protein levels of the shrimp meal (52.7 percent) and of corn (10.2 percent) are averaged with soybean meal and rice
Basal feed = 21.35/39.15 = 54.53%
Protein supplement = 17.8/39.15 = 45.47%
Thus, to make 100 kg of this feed one would mix the following:
Rice bran 27.265 kg
Corn 27.265 kg
Soybean meal 22.735 kg Shrimp meal 22.735 kg
The square method is helpful to novice feed formulators because it can get them started in diet formulation without the need to resort to trial and error. The square method can also be used to To make the 27 percent crude protein carp feed, we must mix 17/35.8 of rice bran with 18.8/35.8
Rice Bran 17/35.8 = 47.5%
Soybean meal 18.8/35.8 = 52.5%
g of this feed we must mix 47.5 kg of rich bran with 52.5 kg of soybean meal.
If more than two feedstuffs are used in a feed, they may be grouped into basal feeds (CP < 20 percent) and protein supplements (CP > 20 percent), averaged within each group, and
into the square method. For example, suppose shrimp meal and corn were also available for the carp feed mentioned above. The crude protein levels of the shrimp meal (52.7 percent) and of corn (10.2 percent) are averaged with soybean meal and rice bran, respectively.
Basal feed = 21.35/39.15 = 54.53%
Protein supplement = 17.8/39.15 = 45.47%
Thus, to make 100 kg of this feed one would mix the following:
The square method is helpful to novice feed formulators because it can get them started in diet formulation without the need to resort to trial and error. The square method can also be used to To make the 27 percent crude protein carp feed, we must mix 17/35.8 of rice bran with 18.8/35.8
Rice Bran 17/35.8 = 47.5%
g of this feed we must mix 47.5 kg of rich bran with 52.5 kg of soybean meal.
If more than two feedstuffs are used in a feed, they may be grouped into basal feeds (CP < 20 percent) and protein supplements (CP > 20 percent), averaged within each group, and plugged into the square method. For example, suppose shrimp meal and corn were also available for the carp feed mentioned above. The crude protein levels of the shrimp meal (52.7 percent) and of
bran, respectively.
Basal feed = 21.35/39.15 = 54.53%
The square method is helpful to novice feed formulators because it can get them started in diet formulation without the need to resort to trial and error. The square method can also be used to
calculate the proportion of feeds tuffs to mix together to achieve a desired dietary energy level as well as a crude protein level
3.3: STEPS IN FEED FORMULATION
The first step in diet formulation is balancing the crude protein and energy levels. This can be accomplished by trial and error, by the square method for either crude protein level or energy level and then adjusting, or by solving simultaneous equations. At first, it is helpful to use at least three feeds tuffs during the initial balancing of protein and energy levels: one high in protein and high in ME, one low or intermediate in protein and high in ME, and one low or intermediate in both protein and ME. Once practice makes one more proficient at diet formulation any number of feedstuffs can be used. One must remember to reserve room in the formulation for any feed additive, such as a vitamin or mineral pre-mix.
The second step in diet formulation is to check the levels of indispensable amino acids in the formulation to be sure the dietary levels meet the requirements of the animal to be fed. The requirements of fish for indispensable amino acids is expressed as the dietary level (as a percent of the diet) or as a percent of the dietary protein level. To convert an amino acid level from the percent of diet to percent of protein, divide the dietary level of each amino acid by the dietary protein level. It might be of interest to calculate the dietary levels of all of the indispensable amino acids, but it is not practical to do it all of the time. If the levels of arginine, lysine, methionine, and tryptophan meet the dietary requirements of the fish to be fed, the levels of the other six indispensable amino acids will most likely be above required levels. When using unconventional protein supplements, the levels of all ten indispensable amino acids should be checked.
If the diet formulation is low in any amino acid, a feedstuff that contains high levels of that amino acid must be added to the diet at the expense of another ingredient. Once the amino acid requirements are met, the dietary protein and energy levels must be rechecked to, see if any substitution of ingredients has imbalanced the formulation.
A diet mixing sheet should be constructed to standardize diet formulation. A sample sheet is shown in Table 1. The amino acids listed are for illustration purposes only and may be changed to suit different circumstances.
In practical feed formulation, pellet quality and acceptability must be considered in addition to nutrient levels and cost. These considerations will vary from species to species and with the type of pellet being made, and are dealt with in other sections of this manual.
3.4: BEST-BUY TECHNIQUES
The price of the feedstuffs used in diet formulations must be considered to formulate a cost-efficient diet. Feedstuffs can be compared with one another on the basis cost per unit of protein,
energy, or amino acid. For example, suppose one has whe
available for a fish diet, which feedstuff would be the least expensive source of energy?
Wheat millrun costs US $ 0.0858/kg, and contains about 1200 kcal ME/kg.
Wheat middlings cost US $ 01883/kg and contain 1663 kcal ME
Thus, the wheat millrun which has a lower ME value for fish is the better buy because it costs less per kcal.
To compare oat groats and wheat middlings on a cost per unit ME basis one would do the following:
Wheat middlings = US$ 0.0001132/kcal,
Oat groats cost US $ 0.2652/kg, and contain about 2450 kcal ME/kg.
Oats groats, although costing more than wheat middlings, constitute a better buy on an energy basis.
The cost of protein is often the greatest part of the cost of a fish diet. Ther savings can be made by using best
supplement. To compare anchovy meal and herring meal, the following calculations are made:
Anchovy meal costs US $ 0.5357/kg, and contains 70.9 perc
Herring meal costs US $ 0.4709/kg, and contains 76.7 percent protein.
On the basis of cost per unit protein, herring meal is less expensive as a dietary ingredient than is anchovy meal.
energy, or amino acid. For example, suppose one has wheat middlings and wheat millrun available for a fish diet, which feedstuff would be the least expensive source of energy?
Wheat millrun costs US $ 0.0858/kg, and contains about 1200 kcal ME/kg.
Wheat middlings cost US $ 01883/kg and contain 1663 kcal ME/kg.
Thus, the wheat millrun which has a lower ME value for fish is the better buy because it costs
To compare oat groats and wheat middlings on a cost per unit ME basis one would do the
Wheat middlings = US$ 0.0001132/kcal, and
Oat groats cost US $ 0.2652/kg, and contain about 2450 kcal ME/kg.
Oats groats, although costing more than wheat middlings, constitute a better buy on an energy
The cost of protein is often the greatest part of the cost of a fish diet. Ther
savings can be made by using best-buy techniques to determinate least expensive protein supplement. To compare anchovy meal and herring meal, the following calculations are made:
Anchovy meal costs US $ 0.5357/kg, and contains 70.9 percent protein.
Herring meal costs US $ 0.4709/kg, and contains 76.7 percent protein.
On the basis of cost per unit protein, herring meal is less expensive as a dietary ingredient than is at middlings and wheat millrun available for a fish diet, which feedstuff would be the least expensive source of energy?
Wheat millrun costs US $ 0.0858/kg, and contains about 1200 kcal ME/kg.
Thus, the wheat millrun which has a lower ME value for fish is the better buy because it costs
To compare oat groats and wheat middlings on a cost per unit ME basis one would do the
Oats groats, although costing more than wheat middlings, constitute a better buy on an energy
The cost of protein is often the greatest part of the cost of a fish diet. Therefore, substantial buy techniques to determinate least expensive protein supplement. To compare anchovy meal and herring meal, the following calculations are made:
On the basis of cost per unit protein, herring meal is less expensive as a dietary ingredient than is
To compare feedstuffs on the basis of cost per unit of an amino acid, one can calculate the best buy in the same way as before.
For example, sesame oil cake which has twice as much methionine content as does groundnut cake on a per unit protein basis would be a more attractive buy at comparable prices.
These kinds of comparisons are only valid if the nutrient in one feedstuff is as valuable or available to the animal as the same nutrient in another feed. Such comparisons should be made whenever prices change.
4.0 Conclusion
For any aquaculture venture to be viable and profitable it must have a regular and adequate supply of balanced artificial diets for the cultured fishes. This is so because the dissolved nutrients that promote primary and secondary production in the natural environment are seasonal and might be insufficient or may not occur in the required proportion to meet the nutritional demand for culture fishes. Supplementary feeding satisfies this need and ensures that fish gets the appropriate spectrum of its basic food requirement for maximum growth.
Supplementary diets are often called artificial diets could be mainly or partially made from natural or synthetic materials. Such preparations are made to meet the nutritional requirement of a particular fish species with provision for fishes of different size/age intervals. Adequate feeding with supplementary diets improves fish resistance to diseases, ensures increase fish production and may enable more than one cropping session per year.
5.0 Summary
Feed formulation is essentially applied nutrition.For formulating feeds for experimental purposes, it is necessary that all ingredients are controlled for all essential nutrients. But, under practical conditions, such a control is difficult to set forth and mostly restricted to rapid proximate composition analyses.Feedstuffs can be compared with one another on the basis cost per unit of protein, energy, or amino acid and the best-buy technique is very effective for this objective. Materials that are cheap and available in large quantity are favoured for fish feed.
Such materials include agricultural and industrial waste e.g. palm-kernel cake, , groundnut cake, milltet/corn ban, rice bran, brewer waste and flour mill sweeping as well as animal waste including chicken offal, blood meal bone meal, shrimp meal and dung. The use of cheap feeds without reduction in effectiveness is desireable in reducing over-head expenses
6.0 Tutor-marked assignment
1. What is feed formulation and account for the choice of ingredient requirement for feed formulation?
2. Write short note on the necessary steps for feed formulation.
3. Elucidate on the term “Best-buy-technique”.
7.0 References/ Further Readings
Ezenwa, B.(1979) Supplementary diets in fish culture and feed formulation technology in Nigeria. Nig. Inst. Oceanogr. Mar. Res. Occ. Pap. No. 30,21p.
Eyo, A.A. (2001). Chemical composition and amino acid content of the commonly available feedstuffs used in fish feeds in Nigeria. Fish Nutrition and Fish Feed Technology in Nigeria (Editor, Eyo, A.A.)Prceedings of the First National Symposium on Fish Nutrition and Fish Feed Technology, Lagos. 1999. Pp 14-22.
Hardy,R.W. (1987). Dietary preparation. In: Fish Nutrition (Ed.J.E. Halver). Academic press inc.. San Diego, California.
Huet, M.V. & D.E. Canfeid Jr. (1972) Textbook of fish culture. Fishing News Books. Survey, England 436pp.
Sherperd, E.J. and N.R Bromage (1988). Intensive fish farming: Nutrition and growth. BSP Professional Book, London, pp 154-195.
MODULE10: INDUCED BREEDING AND HYBRIDIZATION TECHNIQUES
Unit 1: Induced spawning in fish